Photo Essay
Adaptations to wind in the sanddunes
The sanddunes between the Pecos River and the western escarpment of the Llano Estacado are beautiful. The sand has been blown up from the Pecos River Valley for thousands of years. In places dune fields glitter in the bright sun, beckoning inquisitive explorers. Many people, when they visit the Monahans State Park on Interstate 20 and the Mescalero Dunes between Tatum and Roswell are entranced by the patterns of ripples, shadows, and tracks in the sand. In places, the most precious commodity in the world - water - can be found between the dunes under willow trees. If the wind is blowing, however, it becomes one of the most inhospitable places imaginable.
The photographs were taken in late March and early April by members of the 2008 class of the Llano Estacado Chapter of the Texas Master Naturalists. Photographers include Nina McCart, Chris Cherry, Taffy Armstrong, Leslie Harman, Sharon Long, Burr Williams, J.D. Drissell, R.L. Orth, and Sean Patty.
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Was the wind blowing when this photograph was taken? Look at the closer ridge -- it seems to have a fuzzy top of blowing sand. Why isn't the tallest (and farthest) dune in the same condition? Why would the wind be blowing more rapidly at different elevations?
Why did ripples form at the top of the dune, but not on the slope of the dune?
Why are the ripples larger further down this dune? Naturalists always ask questions!
These ripples have two faces - is it a record of wind from two different directions?
Why does the shadow of the dune near the top have lobes? Did the shinoaks create ridges that are not discernable?
In the early morning, after a windy night, some of the dunes are covered with ripples, while others are not. In the lower right, in the foreground, several small bumps are seen. What happened there? In the left foreground is a group of small willows at the crest of a dune.
Near the edge of the dune field, mesquite (in the right foreground), yucca (in the left foreground), and shinoak, (on the dune to the left and at the crest of other dunes) is seen, but open areas of sand cover more surface area.
One of the shinoaks has grown almost ten feet tall. In the foreground are scattered pink sand penstemon, not in bloom yet. Two tall stalks of last year's sunflowers remain, too.
In the foreground are two clumps of big bluestem, whose leaves turn reddish in the winter.
The seedstalks of sanddune yucca (y. campestris) grow among last year's stalks of giant sandreed.
Near more willow at the crest of a dune is a pedastal of big bluestem. Although the wind blew away much of the sand at the base of the grass, the plant continues to live and thrive.
The dust whirls among the willows at the crest of another dune.
Visible sand plumes reach 5 feet away from the dune when the wind is blowing 35 miles an hour.
It is a horrible experience to stand in sand blowing when the wind is howling - it gets in the eyes, in the nose, in the ears, throughout the hair, and even in a person's lungs!
How can the leaves of the willow survive sand blasting the tender tissue?
Another "river of blowing sand" gushes over the lip of a dune. Notice there are two places where the wind forms those "rivers of blowing sand" separated by just a few feet.
The blowing sand is almost like ground fog in an open area - creating a haze that blurs any definition to the scene.
Earlier in the year, the shinoak was leafless on a clear still morning. Just to the left is an open dune field, but most of these tunes are almost completely vegetated. Look on the shinoak in the distance - what is it?
A pyrrhuloxia sang his syrupy song for thirty minutes, as he waited for the sun to heat the air. It was too early in the spring for a female to pay attention.
Chipping sparrows were plentiful in early April of 2008 as they migrated through the sanddune region.
As the mesquite leafed out in the first week of April the curved-bill thrashers sang lustily - bragging about their choice piece of land.
A white-winged dove investigated a pile of brush - had a packrat nest dropped some seeds?
A roadrunner turned its back to the rising sun, lifting its feathers to warm its back.
The sanddune habitat is a favorite of Say's Phoebes, a year around resident in west Texas.
The previous year's bloom stalk of a Buena mujer (mentzelia) grew among the sandreed.
The architecture of the buena mujer seedstalk is intriguing.
In each seed capsule dozens of seeds await to be dumped during a violent thunderstorm.
The tiny leaflets of Dalea greggii cast a bold shadow on the sound. Tiny purple blossoms will appear if enough rain falls. If the leaves are covered by sand, it will continue to send runners up through the sand and leaf out again at the new soil surface.
Are these seedlings? Or are the ends of new shoots from the perennial sundrops (Calylophus drummondii)
When the roots of the sundrops are exposed, a new branch begins to grow from the exposed root.
The new shoots of buena mujer push up through the sand and begin this year's growth. If a stalk breaks off by being hit by a passing animal, it sends up more stalks from a node of the stalk previously buried by the sand.
When the base of a yucca is exposed, the blowing sand becomes attached to the softer and more moist parts of the base of the leaf blades.
The sundrops has soft crinkly tissue-paper like blossoms that last only a few hours.
Prickly poppy is not adapted to being covered by sand. Will it grow to bloom in May?
Jimsonweed grows from large roots. If covered by only a few inches of sand it will continue to grow, but it can be buried and killed if too much sand covers the new growth.
Canaigre (dock) sends up large leaves and a large bloom stalk if enough moisture is present in the dunes, but if not enough moisture is present, the leaves die. Underneath the soil are many large roots that look like sweet potatoes - check out this photoessay for photographs of the roots.
The staff of the Sibley Nature Center does not know what species of plant these new leaves will become - the stems are too big for a seedling sunflower or cocklebur, we believed. We could not think of a perennial plant with leaves of that pattern, however. If you know, tell us!
The orange ball is that of a native tumbleweed - tumble ringwing (Cycloma). It is adapted to having its stems covered by sand, but the introduced tumbleweed (Russian thistle) is not.
Sand rabbitbrush colonizes the more stabilized dunes. It holds on to its seeds until spring - when the winds of West Texas blow the hardest. The little seeds have hairs attached, so the seeds "parachute" for great distances.
Most plants suffer when their leaves are covered by dirt, but not that of Oenethera grandis - an annual evening primrose with large yellow blossoms.
Queen's delight prefers the sanddune habitat. We do not know why such a nondescript plant has such a royal name!
Sensitive briar survives sand blasting its leaves by being sensitive - when touched by anything, the leaflets fold up tight.
The Sibley staff believed these new shoots to be that of Queen's delight that had been buried several inches below the sand, but we might be wrong. We were definitely impressed by the size and vigor of the shoots.
A young cocklebur had already been partially buried by the blowing sands of spring.
Several of the class found this species of plant. It might be a very misplaced Illinois bundleflower, or an out of range wild licorice - neither species should be found in the Monahans dunes. The Sibley staff could not think of any other multitrunked legume with stalks up to four feet tall that is native to the Llano Estacado or its surrounding regions. No thorns were present on the stalks.
When the first week of May comes, the pink sand penstemon will be one of the showiest plants of the region. It only grows in loose sandy soil - which prevents its use as a xeriscape ornamental in southwestern landscapes.
Black willows are scattered throughout the dune region.
Most grow in low areas between the dunes, but even there, sand be caught by its branches and will pile up and form ridges.
In early April the catkins draw many species of early spring insects.
In between the willows in the low areas will be bulrushes (Scirpus.)
Some of the willows will be twenty feet tall or more - which leads to a question - when willows are seen at the crest of a dune, is there twenty or thirty feet of covered tree below the dune?
Seepwillow (baccharis and not a true willow) has become more common in the damp areas between the dunes. Until 1980, seepwillow was rare in the region.
The roots of the willow somehow hold the sand in place to some degree. A sanddune had moved into one of the low areas, but then had stopped. Some of the sand eroded - by wind? By water?
Down among the bulrushes animals had pushed the plants aside to get at water at the ground's surface.
On a cold morning, one of the larger pools was covered by ice.
From the crest of a dune nearby, few would realize water might be found in the low area.
Buckley penstemon is common in the sanddune region west of the Llano Estacado. A deer had found the succulent shoots refreshing, but the plant kept blooming.
An overwintering bumblebee queen gathered the penstemon's nectar to prepare her honeypots for this year's young.
A tiny ground bee worked the flowers, too - in fact, its abdomen can be seen in the previous photograph.
Three shield beetles were on the penstemon, too. Do you see the third one (you can only see its underside.) Was this a mating aggregation - or were they feeding on the penstemon?
A visitor to the dunes had left a plastic bucket - which a spider found to its liking. The spider was unfamiliar to the Sibley staff.
Honeybees loved the water at the intrepretative building at the Monahans State Park.
The buds of the shinoak must have a sticky exudescence - several species of insects spent great periods of time on each bud. This little wasp is an Ammophilia - it digs a hole, places tiny caterpillars in the hole with its eggs, covers up the hole, and then returns to replenish the supply of caterpillars as the larvae eat the caterpillars. These wasps use tiny rocks to pack the sand at the top of their nests - a tool using insect!
Dusky-winged butterflies also liked the buds of the shinoak.
In the gravel along a road in the park ants swarmed over a lizard killed by a passing car, stripping it to nothing but bone. The species of ant was not determined, but they might be Conomyrma, or "crazy ants."
Most of the photographers noticed upraised lines in the sand. The creature that creates the lines has mystified Sibley's executive director for years.
J.D. Drissell discovered the critter creating the tiny ridges when he noticed one of the lines being formed. He swept aside the soil and a tiny wormlike creature was exposed. Sibley staff believe it to be a wireworm, the larvae of a click beetle. After Mr. Drissell exposed the creature, it coiled itself up and rolled down the slope of the dune. When it reached bottom, it quickly dug into the soil and disappeared.
What appears to be a young tarantula walked across the dune, but the identification is only a guess.
Another fuzzy spider crouched, drawing its legs to its body when a photographer disturbed it.
Each of the photographers also noticed this type of track, and believed it to be the trail of a centipede.
The tiny balls of dirt around this small hole led the staff of Sibley to believe a spider was in the hole - for spiders that live underground often ball up the dirt removed from a hole with silk.
The diversity of holes in the sanddunes is amazing. This hole seems to have been shaped by moisture added by the creature doing the work.
A weirdly shaped hole totally mystified the photographer and the Sibley staff.
Despite examining Cokendolpher's work on the ants of the Llano Estacado and Wilson and Holldobler's massive work on ants, the Sibley staff could not decide on an identification for this species of ant which built a raised cone of dirt around their entry hole.
Darkling beetles walk with legs extended so that their body is off of the ground. This may be the trail of one.
Someday someone will spend the amount of time to correlate insect tracks with the insect that left its mark. There are no field guides to the insect tracks of the sanddunes between the Pecos River and the Mescalero Escarpment of the Llano Estacado.
The photographer believed this narrow hole to be where a centipede exited the ground. Centipedes remain deep underground in the more moist levels of the sand, and only emerge when the humidity of the air is high.
The photographers found only one grasshopper during 25+ hours of observation.
No dirt pile was near this hole, but it had a small upraised collar. Its creator is unknown.
Another hole had waste piled at its entrance - but no tracks were visible to give a hint to its maker.
A wolf spider's hole is easy to recognize by the collar of sticks woven together at its mouth. It appears that the spider had been scraping dirt towards the hole - judging by the tiny lines near the hole. Despite the harsh conditions brought by wind, an amazing number of arthropods can be found in the dunes. (And more wait to be discovered - in 2005 a new species of beetle was described from the Monahans dunes - see this essay.)